Description. Type Ammonites raulinianus d'Orbigny, 1841. Wright's description (1996) is succinct and does not cover certain species: a moderately depressed to compressed genus, with lautiform or zigzag ribs ending in oblique ventrolateral clavi, generally forming zigzags on venter. The adult body chamber of macroconchs is smooth, with a rounded venter. Lower Albian of Europe and Transcaspia. We add that the rib terminations are alternate on either side of the siphonal line. Amédro et al. propose the following, clearer classification, in the order of appearance of the successive forms:
Groupe 1. Ribs simple or bifurcated, curved forward, with oblique forward ventral terminations. Examples: Otohoplites guersanti (d'Orbigny, 1841) and five species from Casey (1965): O. involutus, O. maxinae, O. oweni, O. simplex, O. waltoni (= O. larcheri Destombes, 1979). P. (H.) puzosianus zone and base of O. subhilli zone.
Groupe 2. Zigzag, bifurcated, or more rarely lautiform ribs, with oblique forward ventral projections. Examples: O. raulinianus (d'Orbigny, 1841, upper photograph) and O. subchloris Casey, 1965. P. (H.) puzosianus zone.
Groupe 3. Lautiform ribs which end on ventrolateral tubercles pinched in clavi, oblique to the siphonal line. Examples: two species from Spath (1925a) (Otohoplites auritiformis and O. elegans) and four from Casey (1965): O. glyphus, O. icarus, O. polygonalis and O. subguersanti. P. (H.) puzosianus zone.
Groupe 4. Lautiform ribs terminating in pinched ventrolateral tubercles, forming clavi parallel to the siphonal line on outer whorls. Example: the zone ammonite O. subhilli (Spath, 1942, lower photograph) of which O. destombesi Casey, 1965, and O. bulliensis Destombes, 1973, are junior synonyms.
Groupe 5. Ribs simple or bifurcated, strongly projecting forward on the outer third of the flank, with prominent ventral rib terminations, oblique forward. Example: type O. normanniae Destombes, Juignet & Rioult, 1974. Upper part of the subhilli zone and lower third of the steinmanni zone.
Remarks. By comparing photos, Owen (1988) connects O. sinzowi Saveliev, 1973, to O. auritiformis and O. venustus Saveliev, 1973 to O. subhilli. O. crassus Saveliev, 1973, would also be a synonym of O. subhilli (Amédro et al., 2014). I'm doubtful: I have an O. sinzowi from Mangystau and an O. subhilli from Bully which look identical.